There is no picture for me to know what part is labeled b
The answer is 50 percent.
Parent plant of genotype Rr will in meiosis produce haploid gametes which will carry either R allele or r allele. Since there are only two possibilities R or r, the probability that seed will get r gene is 1 of 2. This can be presented as 1/2, which is 50%.
Primary succession is a method of fertilizing soil that was barren and had never supported plant life, for example soil left over by a moved glacier of lava.
The soil is first "normalized", using pioneer species such as lichens, algae and fungi.
After this, plants able to survive in less harsh conditions such as grasses.
Therefore, the fertility of soil during early years of primary succession does not increase much and it is a process that involves a long period of time.
Radiocarbon is the most common.